LA JOLLA—Chronic liver disease represents a major global public health problem affecting an estimated 844 million people, according to the World Health Organization. It is among the top causes of mortality in Australia, the UK and the United States. At the same time, it is both difficult to manage and there is no FDA-approved anti-fibrotic liver therapy. The microbiome—a complex collection of microbes that inhabit the gut—may be an unexpected indictor of health. Now, a collaborative team of Salk Institute and UC San Diego scientists have created a novel microbiome-based diagnostic tool that, with the accuracy of the best physicians, quickly and inexpensively identifies liver fibrosis and cirrhosis over 90 percent of the time in human patients.